Abstract: An idle speed control for an engine includes an improved construction. An air induction system for the engine has a plurality of main air intake passages. Each one of the intake passages has its own throttle valve therein. An idle air manifold is disposed for supplying air charges to combustion chambers of the engine through delivery conduits. Amounts of air charges flowing therethrough is controlled by a feedback control system. The sum of cross-sectional areas of the delivery conduits is greater than a cross-sectional area of an inlet portion of the idle air manifold. The respective delivery conduits have restrictions upstream of junctions to the air intake passages.

Abstract: An engine idle control system includes an improved construction for changing an aimed idle engine speed, which is preset by the manufacturer therein, in response to various needs of a user. The engine has a main passage having a throttle valve therein and a bypass passage arranged to bypass the throttle valve. The bypass passage supplies an idle air charge to a combustion chamber of the engine when the throttle valve is generally closed and has an adjusting valve therein for adjusting the idle air charge. A control device controls the adjusting valve to reduce a difference between an actual idle speed sensed by an engine speed sensor and an aimed idle speed preset in the control device. The control device includes means for changing the aimed idle speed.

Abstract: An outboard motor has an induction system and a fuel supply system. The two systems are linked together to improve responsiveness of the fuel supply system based upon fluctuations in pressure within the induction system. The motor includes an induction air pressure detection system. The detection system comprises a pressure sensor and a connection to at least two different air intake pipes of the induction system. The connection between the sensor and the two pipes is configured such that the distance between the sensor and each of the pipes is the same. The detection system is configured to sample the pressure in multiple intake pipes associated with multiple cylinders using connecting conduits that have the same length from each intake pipe to the pressure sensor.

Abstract: A shifting mechanism for an outboard drive of a watercraft provides reduced coupling shock when the forward gears are engaged by a dual clutch assembly, as well as provides for consistent and quick engagement of the clutch assembly with the gear. The shifting mechanism involves a first gear and a corresponding first clutch, and a second gear and a corresponding second clutch. A plunger carries the first and second clutches which are arranged on the plunger at unequal distances from their respective gears. This nonuniform spacial relationship between the clutches and gears causes one clutch to engage its corresponding gear before the other clutch engages its corresponding gear. The staggered engagement decreases shock on the transmission and permits quicker engagement between the clutches and gears.

Abstract: A lower unit for an outboard drive has an elongated length in order to present a streamline shape while providing sufficient width to house a transmission for a counter-rotational propeller system with a forwardly-oriented clutch element. One of the clutch elements of the transmission lies in front of the transmission gears to increase the flow area through an exhaust discharge path behind the transmission. In order to accommodate this transmission structure, the lower unit has an increased with at a point forward of the associated drive shaft. The lower unit also has an increased length as measured from the drive shaft forward in order to present a streamline shape within the water. The elongated length of the lower unit also improves the directional and rolling stability of the outboard drive.

Abstract: Two embodiments of silencing devices for a marine propulsion unit that include an engine surrounded by a protective cowling and which is adapted to be detachably connected to the hull of the watercraft. The silencing devices include at least one expansion chamber positioned within the hull and connected to the interior of the protective cowling by a duct. The devices are tuned to silence the noises emanating from the engine which include the induction system noises and/or mechanical noises.

Abstract: A transmission system for a counter-rotational propulsion device is easily incorporated into an existing outboard drive of a watercraft to convert the outboard drive from a single propeller drive to a counter-rotational dual propeller system. The transmission system involves a first transmission which selectively couples an inner propulsion shaft with an existing drive shaft of the outboard drive. The inner propulsion shaft in turn drives a rear propeller. A second transmission of the transmission system is provided between the inner propulsion shaft and an outer propulsion shaft. The second transmission reverses the rotational drive direction input by the inner propulsion shaft so as to drive the outer propulsion shaft in an opposite rotational direction. The outer propulsion shaft drives a front propeller which spins in an opposite direction to that of the rear propeller, but asserts a thrust in the same direction as the rear propeller.

Abstract: A shifting mechanism for an outboard drive of a watercraft provides reduced coupling shock when the forward gears are engaged by a dual clutch assembly, as well as provides for consistent and quick engagement of the clutch assembly with the gear. The shifting mechanism involves a first gear and a corresponding first clutch, and a second gear and a corresponding second clutch. A plunger carries the first and second clutches which are arranged on the plunger at unequal distances from their respective gears. This nonuniform spacial relationship between the clutches and gears causes one clutch to engage its corresponding gear before the other clutch engages its corresponding gear. The staggered engagement decreases shock on the transmission and permits quicker engagement between the clutches and gears.

Abstract: A shifting mechanism for an outboard drive of a watercraft provides reduced coupling shock when the forward gears are engaged by a dual clutch assembly, as well as provides for consistent and quick engagement of the clutch assembly with the gear. The shifting mechanism involves a first gear and a corresponding first clutch, and a second gear and a corresponding second clutch. A plunger carries the first and second clutches which are arranged on the plunger at unequal distances from their respective gears. This nonuniform spacial relationship between the clutches and gears causes one clutch to engage its corresponding gear before the other clutch engages its corresponding gear. The staggered engagement decreases shock on the transmission and permits quicker engagement between the clutches and gears.

Abstract: A hydraulic steering system for a marine propulsion outboard drive that includes a manually operated bypass passage interposed between the fluid chambers of the hydraulic steering motor so as to facilitate manual steering of the outboard drive.

Abstract: An outboard motor having a power head in which an exhaust expansion chamber is provided that receives the exhaust gases from the engine and delivers them to an underwater exhaust gas discharge. The expansion chamber is affixed to the engine and forms at least in part a closure for an exhaust manifold formed integrally in the engine cylinder block.

Abstract: A small watercraft having a number of embodiments of exhaust systems into which coolant from the engine are discharged and which insure that water cannot enter the exhaust ports in the event the watercraft becomes displaced. In all embodiments, a water accumulating volume surrounds the discharge end of the exhaust pipe within an expansion chamber for trapping water in the event the watercraft becomes displaced from its normal condition and for return of the water therefrom upon erection of the watercraft. In a number of embodiments, gravity operated normally open control valves are also provided for closing the end of the exhaust pipe in the event the watercraft becomes displaced from its normal upright condition so as to insure that water cannot enter the exhaust ports of the engine.

Abstract: Several embodiments of outboard motor fuel feed systems wherein a position responsive valve is interposed between a remotely positioned fuel tank and the engine charge former for precluding the inadvertent flow of fuel to the charge former when the outboard motor is tilted up. In one embodiment, the valve is a gravity responsive valve and in another embodiment, the valve is mechanically operated. In a third embodiment, a device is provided for relieving the pressure in the conduit between the position responsive valve and the fuel tank when the outboard motor is again tilted down to its normal running position.

Abstract: Several embodiments of outboard motor fuel feed systems wherein a position responsive valve is interposed between a remotely positioned fuel tank and the engine charge former for precluding the inadvertant flow of fuel to the charge former when the outboard motor is tilted up. In each embodiment, the valve is a gravity responsive valve and in another embodiment a pressure responsive valve member is provided for ensuring fuel flow when the outboard motor is again tilted down to its normal running position.